Refrigerating apparatus



Aug. 8, 1933- M. w. KENNEY ET AL REFRIGERATING APPARATUS Filed June 30, 1930 INVENTORS Y 0 w W E. r m l g w e i p Z T w j w a 6 P m w & E m m L m S N E D W c CoM /esssae Patented Aug. 8, 1933 UNITED STATES.

PATENT OFFICE Vickers, Norwood Park,

Ill., assignors, by mesne assignments, to Grigsby-Grunow Company, a

Corporation of Illinois Application June 30, 1930. Serial No. 464,882

11 Claims.

This invention relates to refrigerating apparatus used in systems of the compression expansion type, especially where a flooded evaporator is used. In systems of this character lubricant used in the compression mingles with refrigerant and in time is carried through the 'entire system of compressor, condenser, evaporator and associated conduits.

In the type of system where lubricant and refrigerant dissolve in each other to only a limited extent, and where the lubricant would normally float on the liquid refrigerant, as is the case with sulphur dioxide, the presence of any considerable quantity of lubricant in the evaporator is a serious problem. The lubricant, which itself has no tendency to evaporate under evaporator conditions, spreads over the surface of liquid refrigerant and tends to inhibit evaporation thereof. Where refrigerant gasifies under such conditions it is evident that the evaporator is laboring under a load, which seriously reduces its eficiency. Furthermore, any lubricant remaining in the evaporator represents that much less in the compressor where it is actually needed.

In systems where lubricant and refrigerant form a true mixture, it is clear that the continued boiling off of refrigerant in the evaporator will finally tend to leave a substantially pure body of oil. In case the lubricant is heavier than the refrigerant, lubricant will constantly collect in the evaporator, displacing more and more of the normal liquid refrigerant therein and gradually tending to reduce the efliciency of the entire refrigerating system.

In order to control or remove lubricant from the evaporator, various expedients have been tried. Thus, where the lubricant is heavier than refrigerant, it has been proposed to have a conduit leading to the compressor communicating with the lower layers of liquid. A float buoyant in lubricant only controls a valve in the oil return conduit. It is obvious that such an expedient necessitates the presence of an appreciable layer of oil or incurs the risk of wasting liquid refrigerant by drawing it into the compressor.

Where lubricant floats on the refrigerant, which is usually the case in household refrigerating systems, a somewhat similar expedient has been tried, wherein a float carries the open end of an oil intake conduit. By suitable calibration the lubricant intake is supposed to be positioned above the layer of liquid refrigerant, where any oil might normally float. This expedient has been modified by disposing a float controlled cup or pan whose rim is supposed to lie just above the junction of the refrigerant and oil surfaces. A gas intake pipe dipping into the pan sucks out oil which has over-flowed into this skimmer.

All these expedients are objectionable because of their inefiiciency, their tendency to maintain a predetermined layer of oil, and the presence of mechanical elements requiring careful adjustment with regard to size and weight, thus making the cost of such apparatus high.

Another expedient involves the disposition of a lubricant intake at a fixed point, usually above the normal level of refrigerant. This system, in common with the others, besides maintaining a predetermined quantity of oil, loses greatly in efliciency the more violent the ebullition that occurs within the evaporator.

It is clear that the disposition of lubricant intakes with regard to arbitrary levels involves a smooth liquid surface. In practice, when the compressor is operating, the reduced pressure in the gas space of the evaporator is sufficient to cause violent boiling of the refrigerant. Under such conditions it becomes practically impossible to prevent the return of liquid refrigerant to the compressor.

An object of this invention is to devise a means and method for removing oil from an evaporator in a highly efficient and simple manner. A further object is to devise a means and method of removing oil from an evaporator that will be generally applicable to all kinds of refrigerants and lubricant. An additional object is to accomplish both with a minimum amount of apparatus.

In its broader aspects, this invention contemplates the removal of lubricant from the evaporator in the form of a fine mist. Such removal has great advantage since no danger is incurred with respect to the compressor mechanism usually present when an incompressible liquid is sucked into the mechanism.

In general, I divide the gas space in the evaporator and gas outlet conduit into a plurality of regions. At the dividing surfaces I maintain liquid in a highly attenuated form. Upon opera-, tion of the compressor, gasified refrigerant is sucked through the dividing surfaces. The liquid at the dividing walls may consist of refrigerant and lubricant indiscriminately. Whatever liquid refrigerant exists in this highly attenuated form is evaporated because of the low pressure existing during the operation of the compressor. The remaining liquid, consisting of lubricant, is in such highly attenuated form that when the compressor operates the rush of gas through the dividing wall is sufficient to mechanically entrain the lubricant as a fine mist and return it to the compressor. The tendency of the highly attenuated liquid wall to constantly regenerate itself results in a substantially complete and speedy removal of lubricant from the evaporator.

In order to practice the invention, it is unnecessary to maintain any predetermined quantity of lubricant within the evaporator. The result of this invention is to remove lubricant substantiif the lubricant is heavier than the refrigerant,

it would be desirable to extend the capillary means to the lower lubricant layer.

Such provisions are not necessities, since reliance may be had upon the violent agitation of the liquid during evaporation to throw enough liquid on the dividing wall so that the film will constantly be regenerated.

In the description which follows, while the invention has been described in connection with a refrigerant, which is heavier than lubricant, and where the dividing wall contacts with the surface liquid, it is to be understood that this is merely the preferred form of the invention and is not necessarily to be limited thereto.

In the drawing,

, Figure 1 is a ating system; and

Figure 2 is a detail of a modification.

The refrigerating system comprises the usual compressor, discharging into a condenser which is adapted to supply liquid refrigerant to an evaporator. The evaporator is connected by a conduit 1 to the intake of the compressor, the evaporator itselfcomprises a cylindrical dome 2, from which depends a plurality of pipe loops'3.

Gas dome 2 of the evaporator has a liquid refrigerant inlet pipe 10 connected thereto and terminating in a valve seat 11. A float valve strucu u tic view of a refrigerture 12 carrying a valve 13 is adapted to maintain a substantially constant level of liquid within dome 2. Gas outlet pipe 1 has its open end in the gas space of the evaporator and is covered by a gauze member 20. This member is shown as tubular in shape, and of the same size as outlet pipe 1. It is obvious, however, that both the size and shape may be varied to suit different conditions. It will be noted that member 20 dips below. the surface of the liquid but has a sufficient area in the gas space so that when the compressor is operating there will be no tendency to suck liquid This wiclclng preferably extends upwardly from the liquid though cross wicks may be provided if desired. In some instances it may be desirable to incorporate within screen 20 a quantity of wicking in loose form, to function as an additional barrier and break up any large drops of liquid.

It is obvious that, instead of wiregauze, member 20 may be thin wood or of fabric maintained in place by stiff wires. This is shown in Figure 2 where a wire framework 30 supports a fabric wall 31.

While I have shown the dividing wall comprising gauze member 20 as directly connected to the end of outlet pipe 1, it is obvious that this need not necessarily be. Member 20 may be supported in any suitable fashion, and need only function as a foraminous partition between a plurality of gas regions.

In operation, whatever oil that may be present in the neighborhood of member 20 will be drawn up by capillary attraction and spread out as a highly attenuated film in the gas stream.

We claim:

1. In a refrigerating apparatus of the compression expansion type wherein lubricant and refrigerant mingle the combination of a flooded evaporator having a gas outlet pipe therefrom and capillary means separating the gas space within the evaporator from the space within the outlet pipe for removing lubricant from the evaporator.

2. In a refrigerating apparatus of the compression expansion type in which lubricant and refrigerant mingle, the combination of a flooded evaporator having a gas outlet and capillary means forming a separating wall between the gas space within the evaporator and the inside of the outlet.

3. A refrigerating system comprising a compressor adapted to operate upon refrigerant in the presence of lubricant, a condenser into which said compressor discharges, an evaporator of the flooded type connected to said condenser, a gas return conduit connected from said evaporator to the intake of said compressor, said return conduit opening into a gas space in the evaporator and capillary material bridging the space between the return conduit and the surface of the liquid to separate the evaporator gas space from the gas space within the return conduit and functioning as a separating wall through which gas from the evaporator must pass to the return conduit.

4. In a refrigerating system of the compression expansion type, wherein lubricant and refrigerant mingle, the combination of a flooded evaporator having an inlet pipe for liquid refrigerant and a gas outlet pipe and a perforatedmember having capillary material therein connected to the gas return pipe and forming a barrier through which gas from the evaporator 5 to the return pipe must pass. i

5. In a refrigerating system of the compression expansion type the combination of a flooded evaporator having inlet and outlet conduits for liquid and gas refrigerant respectively and a capillary barrier disposed at the end of said outlet pipe through which gas from the evaporator passes.

6. In a refrigerating system of the compression expansion type a flooded evaporator having I a liquid refrigerant inlet and gas outlet, a screen member disposed over the end of said gas outlet said screen member dipping into the liquid but having suflicient area in the gas space so that substantially all gas from the evaporator passes through said screen without aspirating any liquid within said screen member.

7. In. a refrigerating system of the compression expansion type a flooded evaporator having a liquid refrigerant inlet and gas outlet a screen member disposed around the end of said gas outlet and dipping in said liquid and capillary means disposed on the surface of said screen member.

8. In a refrigerating system of the compression expansion type where lubricant and refrigerant mingle and having a flooded type of evaporator, the method of removing oil from evaporator which consists in dividing the gas space within said evaporator into a plurality of separate regions maintaining a wall of liquid in a highly attenuated form at the dividing surfaces and sucking evaporated refrigerant through said liquid walls. I

9. In a refrigerating system of the compression expansion type wherein lubricant and refrigerant mingle and having a flooded evaporator, the method of removing oil from the evaporator which consists in dividing the gas space within said evaporator into a plurality of distinct regions by capillary means and drawing evaporated refrigerant through said capillary means. 7

10. In a refrigerating system of the compression expansion type wherein refrigerant and lubricant mingle and having a flooded type of evaporator, the method of removing oil from the evaporator which consists in forming a finely divided foraminous barrier, wetting said barrier with liquid and sucking evaporated refrigerant from there through said barrier.

11. In a refrigerating system of the compression expansion type wherein lubricant and refrigerant mingle and having a flooded type of evaporator, the method of removing oil from the evaporator and returning it to the compressor which comprises forming a capillary barrier between the gas space in the evaporator and return conduit, wetting said barrier with liquid and sucking evaporated refrigerant therethrough.

MAHLON W. ENNEY. S ERNEST VICKERS. 

